Self-closing pneumatic spring system

ABSTRACT

The invention relates to a pneumatic spring system ( 1 ) comprising at least the following components, specifically: a pneumatic spring cover ( 2 ) and a pneumatic spring piston ( 4 ), which are arranged opposing each other; a pneumatic spring bellows ( 3 ) made of elastomer material, which connects the pneumatic spring cover ( 2 ) and the pneumatic spring piston ( 4 ) with each other with the use of fasteners ( 8 ), whereby the bellows is capable of rolling off on the outer wall of the piston ( 5 ) with formation of an internal chamber ( 6 ) of the pneumatic spring having an elastic volume; as well as a connection ( 7 ) for ventilating and evacuating the internal chamber ( 6 ) of the pneumatic spring. The pneumatic spring system is equipped with a pressure-sensitive connection system which reacts to pressure in a way such that in the evacuated condition, the pneumatic spring cover ( 2 ) and the pneumatic spring piston ( 4 ) are connected with each other, whereby the connection is released again in the operating conditions, i.e. when the internal chamber ( 6 ) of the pneumatic spring is filled with air.

CROSS REFERENCE TO RELATED APPLICATIONS

Applicant claims priority under 35 U.S.C. §119 of German Application No.199 31 195.1, filed Jul. 7, 1999. Applicant also claims priority under35 U.S.C. §120 of PCT/DE00/01324, filed Apr. 27, 2000. The internationalapplication under PCT article 21(2) was not published in English.

BACKGROUND OF THE INVENTION

1.Field of the Invention

The invention relates to a pneumatic spring system comprising at leastthe following components, specifically

a pneumatic spring cover and a pneumatic spring piston, which arearranged opposing each other;

a pneumatic spring bellows made of elastomer material, which connectsthe pneumatic spring cover and the pneumatic spring piston with eachother with the use of fastening means, said pneumatic spring bellowsbeing provided with an embedded reinforcement in most cases, whereby thebellows is capable of rolling off on the outer wall of the piston withformation of an interior chamber of the pneumatic spring having anelastic volume; as well as

a connection for ventilating and evacuating the interior chamber of thepneumatic spring.

2.The Prior Art

A pneumatic spring system of said type is described, for example in thepublished patent documents DE 42 28 513 A1 and WO 98/54016 A1.

Pneumatic spring systems may be in the following two conditions:

(a) Filled with air (operating condition), or

(b) evacuated.

Now, the following problem is posed in conjunction with pneumatic springsystems of vehicles, in particular with vehicles that are lifted by acrane. When the vehicle is set down again, the bellows of the pneumaticspring system often no longer rolls off correctly on the outer wall ofthe roll-off piston. The consequence thereof are damage caused to thebellows of the pneumatic spring system and also to other components,which may then lead to total failure of a pneumatic spring system.Particularly critical is in this conjunction the condition (b) in whichthe vehicle is lifted by the crane.

Now, the problem of the invention against the background of saidproblems consists in providing a pneumatic spring system of the typespecified above that is self-closing, so that the vehicle can be liftedby the crane when the pneumatic spring system is in the condition (b)without causing damage to the pneumatic spring system, but the latterwill be fully operational again when it is in the condition (a).

SUMMARY OF THE INVENTION

Said problem is solved in that

the pneumatic spring system is equipped with a pressure-sensitiveconnection system that is located within the internal chamber of thepneumatic spring and reacts to pressure in a way such that the pneumaticspring cover and the pneumatic spring piston are connected with eachother when the system is in the evacuated condition, and that saidconnection is released again by the internal pressure when the system isin the operating condition, i.e. when the internal chamber of thepneumatic spring is filled with air.

BRIEF DESCRIPTION OF THE DRAWINGS

Now, the invention is explained in the following with the help ofexemplified embodiments and by reference to three drawings, in which:

FIG. 1 shows an axial section through an evacuated pneumatic springsystem with the connection system closed;

FIG. 2 shows an axial section through a pneumatic spring system with theconnection shystem open (operating condition);

FIG. 3 shows a radial section through a pneumatic spring system withinthe zone of the diaphragm and thr gpring element (operating condition).

FIG. 4 shows a radial section as in FIG. 3 of another embodiment of theinvention.

The following list of reference numerals applies in conjunction with theabove figures:

1 Pneumatic spring system

2 Pneumatic spring cover

3 Pneumatic spring bellows made of elastomer material

4 Pneumatic spring piston (roll-off or immersion piston

5 Outer wall of pneumatic spring piston (roll-off zone)

6 Internal chamber of pneumatic spring

7 Connection for ventilating and evacuating the internal chamber of thepneumatic spring

8 Fastening means for fastening the pneumatic spring bellows

9 Pressure-sensitive connection system

10 Connection rod

11 Barb

12 Pressure-sensitive closing element

13 Internal cylinder

14 Outer side of internal cylinder

15 Lateral breakthrough

16 External cylinder (inner housing of roll-off cylinder)

17 Interior side of external cylinder

18 Cylindrical diaphragm made of elastomer material

19 Fastening means for diaphragm

20 Spring element

21 Spring arm

22 Stop

23 Flange-shaped widening of internal cylinder

24 Flange-shaped widening of external cylinder

25 Stop buffer

26 Funnel-shaped breakthrough

27 Support

28

DETAILED DESCRIPTION THE PREFERRED EMBODIMENT

FIG. 1 shows a pneumatic spring system 1, whereby a pressure-sensitiveconnection system 9 is located within the internal chamber 6 of thepneumatic spring. Said system consists in this conjunction of aconnection rod 10, which is secured on the inner side and centered onthe pneumatic spring cover 2, and which is provided with a barb 11located within the connection zone. Said system, furthermore, comprisesa pressure-sensitive connection element 12, which is integrated withinthe pneumatic spring piston 4 and in turn comprises the followingcomponents, specifically

an internal cylinder 13 for receiving the connection rod 10, whereby theinternal cylinder is at least provided with the two lateralbreakthroughs 15;

an external cylinder 16, which, in the present case, at the same timeforms the inner housing of the pneumatic spring piston;

a cylindrically shaped diaphragm 18 made of elastomer material, which isarranged between the internal cylinder 13 and the external cylinder 16,and which is secured with each of its ends on the outer side 14 of theinternal cylinder 13 with the use of the fastening means 19; and

at least two spring elements each consisting of a spring arm 21 and astop 22, the latter projecting into the corresponding breakthrough 15 ofthe internal cylinder 13, whereby in the evacuated condition accordingto FIG. 1, the spring element is completely pressed against the outerside 14 of the internal cylinder 13 by means of the diaphragm 18, sothat the stop 22 projecting into the breakthrough 15 comes to restbehind the barb 11 of the connection rod 10 and thus effects theclosure.

The diaphragm 13 is equipped particularly within its fastening area(fastening means 19) with an embedded reinforcement that consists of asubstantially non-expandable material. The pressure-sensitive part ofthe diaphragm 18, thus the zone located between the fastening means 19,however, is free of any reinforcement in order to prevent theflexibility of the diaphragm from being impaired.

Furthermore, the internal cylinder 13 is provided at its top end with aflange-shaped widening 23 that rests on a flange-shaped widening 24 ofthe external cylinder 16. In turn, a stop buffer 25 made of elastomermaterial rests on the widening 23. Said stop buffer is provided with acenter, funnel-shaped breakthrough 26 for the connection rod 10. Alimitation of the path is achieved in this way in the event the barb 11,during the closing process, immerses into the internal cylinder 13 toodeeply and thus too far beyond the stop 22 of the spring element. Abuffer action is effected at the same time versus the pneumatic springcover 2.

The sensitivity of the connection system 9 to pressure is adjusted in away such that said connection will close also in the event a minimalexcess pressure has remained in the internal chamber 6 of the pneumaticspring, so that the pneumatic spring cover 2 is connected with thepneumatic spring piston 4 even if no complete evacuation has occurred.

The pneumatic spring cover 2 is provided with a connection 7 forventilating and evacuating the internal chamber 6 of the pneumaticspring. Although this is the most frequently employed system principle,the connection may be located also on another component of the pneumaticspring, for example on the pneumatic spring bellows 3 (DE 42 26 513 A1).The connection is usually valve-controlled.

Now, FIG. 2 shows a pneumatic spring system in the operating condition,in which the connection rod 10 with the barb 11 is extended. Thediaphragm 18 now rests against the inner side 17 of the externalcylinder 16. This causes the spring element 20, which comprises thespring arm 21 and the stop 22, to release the internal cylinder 13 inthat the stop 22 now still projects in the breakthrough 15 only partly(i.e. not in a closing manner).

An additional support 27 (FIG. 1) for supporting the diaphragm in theoperating condition may be provided between the internal cylinder 13 andthe external cylinder 16, specifically within the zone where thediaphragm 18 is secured.

Now, FIG. 3 shows the pneumatic spring piston 4 with the externalcylinder 16, with the cylindrically shaped diaphragm 18 resting againstthe inner side 17 of said external cylinder in the operating condition.

Within the framework of a particularly useful embodiment, three springelements are provided, which are arranged with the spacing of one thirdof a circle between each other, whereby the three correspondingbreakthroughs 15 are associated with the total of three stops 22. Theinternal cylinder 13 is released in said condition. FIG. 4 shows anotherembodiment wherein there are four spring elements 20 arranged spaced bya fourth part of a circle from one another, and four correspondingbreakthroughs 15 are associated with a total of four stops 22.

What is claimed is:
 1. A pneumatic spring system (1) comprising: apneumatic spring cover (2) and a pneumatic spring piston (4), which arearranged opposing each other; a pneumatic spring bellows (3) made ofelastomer material, which connects the pneumatic spring cover (2) andthe pneumatic spring piston (4) with each other with the use offastening means (8), and which is provided with an embeddedreinforcement, wherein the bellows rolls off on the outer wall (5) ofthe piston with formation of an internal chamber (6) of the pneumaticspring having an elastic volume; a connection (7) for ventilating andevacuating the internal chamber (6) of the pneumatic spring; apressure-sensitive connection system, disposed within the internalchamber (6) of the pneumatic spring and reacting to pressure so that inthe evacuated condition, the pneumatic spring cover (2) and thepneumatic spring piston (6) are connected with each other, wherein theconnection is released again by the internal pressure in the operatingcondition when the internal chamber (6) of the pneumatic spring isfilled with air, said pressure-sensitive connection system comprising: aconnection rod (10), which is provided within a zone of connection witha barb (11)), and a pressure-sensitive closing element (12), which isengaged in a locking manner by the barb (11) of the connection rod (10)in the evacuated condition.
 2. The pneumatic spring system according toclaim 1, characterized in that the pressure-sensitive closing element(12) comprises at least the following components: an internal cylinder(13) for receiving the connection rod (10), whereby the internalcylinder is provided with at least one lateral breakthrough (15); anexternal cylinder (16); a cylindrically shaped diaphragm (18) made ofelastomer material, which is connected with each end with the outer side(14) of the internal cylinder (13) via fastening means (19), and which,in the operating condition, rests against the inner side (17) of theexternal cylinder (16) with simultaneous release of the internalcylinder (13); and at least one spring element (20), wherein each springelement consists of a spring arm (21) and a stop (22), said stopprojecting into the corresponding breakthrough (15) of the internalcylinder (13), wherein in the evacuated condition, the spring element iscompletely pressed against the outer side (14) of the internal cylinder(13) by the diaphragm (18), so that the stop (22) projecting into thebreakthrough (15) comes to rest behind the connection rod (10) and thuseffects closure.
 3. The pneumatic spring system according to claim 2,wherein two spring elements (20) are provided, said spring elementsbeing arranged opposing each other, wherein two correspondingbreakthroughs (15) are associated with a total of two stops (22).
 4. Thepneumatic spring system according to claim 2, wherein three springelements (20) are provided, said spring elements being arranged spacedby a third part of a circle from each other, wherein three correspondingbreakthroughs (15) are associated with a total of three stops (22). 5.The pneumatic spring system according to claim 2, wherein four springelements (20) are provided, said spring elements being arranged spacedby a fourth part of a circle from each other, whereby four correspondingbreakthroughs (15) are associated with a total of four stops (22). 6.The pneumatic spring system according to claim 2, wherein thepressure-sensitive closing element (12) is integrated within thepneumatic spring piston (4), whereas the connection rod (10) is securedon the inner side and centered on the pneumatic spring cover (2).
 7. Thepneumatic spring system according to claim 6, wherein the externalcylinder (16) of the pressure-sensitive closing element (12) forms theinner housing of the pneumatic spring piston (4).
 8. The pneumaticspring system according to claim 2, wherein the internal cylinder (13)is provided at a top end with a flange-shaped widening (23), saidwidening resting on a flange-shaped widening (24) of the externalcylinder (16).
 9. The pneumatic spring system according to claim 8,wherein the pressure-sensitive connection system (9) is provided with astop buffer (25) made of elastomer material.
 10. The pneumatic springsystem according to claim 9, wherein the stop buffer (25) rests on theflange-shaped widening (23) of the internal cylinder (13) and isprovided with a center breakthrough (26) for the connection rod (10).11. The pneumatic spring system according to claim 10, wherein thecenter breakthrough (26) has the shape of a funnel.
 12. The pneumaticspring system according to claim 2, wherein the diaphragm (18) isequipped within a fastening zone with an embedded reinforcement, whereasa pressure-sensitive part of the diaphragm is free of a reinforcement.13. The pneumatic spring system according to claim 12, wherein thereinforcement consists of a substantially non-expandable material. 14.The pneumatic spring system according to claim 12, wherein an additionalsupport (27) is provided for the diaphragm between the internal cylinder(13) and the external cylinder (16), specifically within the fasteningzone of the diaphragm (18), for supporting the latter in the operatingcondition.
 15. The pneumatic spring system according to claim 1, whereinthe pressure sensitivity of the connection system (9) is adjusted sothat said pneumatic spring system also closes when a minimal excesspressure has remained in the internal chamber (6) of the pneumaticspring, so that the pneumatic spring cover (2) is connected with thepneumatic spring piston (4) even in the presence of incompleteevacuation.